Pliant media blasting device

ABSTRACT

The invention relates to a pliant particulate media device which includes an air source for supplying air pressure to a supply container, containing a quantity of pliant blasting media, and a discharge line. The container is connected with a mechanical feed device that positively meters out a desired quantity of blasting media into a discharge line which conveys the blasting media to a discharge nozzle where it is discharged against a surface to be treated to achieve the desired treatment. The invention additionally relates to a recovery system for separating the pliant blasting media from the debris and the other unwanted materials and a system for removing undesired liquids and chemicals from the pliant blasting media after use.

CROSS REFERENCE TO RELATED APPLICATION

This is a continuation in part of application Ser. No. 376,764 filedJul. 7, 1990, now abandoned.

The present invention relates to an improved blasting device forcleaning, degreasing and/or desooting a surface by using a pliantmaterial of a desired porosity and size which is propelled by airpressure to impact against the surface and provide the necessary surfacetreatment.

DISCUSSION OF THE PRIOR ART

A variety of blasting devices are known in the prior art and suchdevices typically dispense materials which are relatively abrasive andheavy. The following six patents depict blasting devices and methodswhich are typical of the prior art.

U.S. Pat. No. 2,426,072 issued to Ridgewood et al on Aug. 19, 1947relates to a method of projecting solid particles at high velocityagainst a surface to achieve the necessary cleaning. The disclosedprojected particles are solid particles consisting of a synthetic resinhaving a desired impact strength and elongation and the contemplatedmaterials are polymers.

U.S. Pat. No. 2,624,988 issued to Vander Wal on Jan. 13, 1953 relates toa polishing and buffering liquid composition which is supplied at apressure of approximately 200 pounds per square inch. The liquidcomposition is discharged, via flexible conduits, through nozzles andimpinges on the article to be cleaned, and this can be seen in FIGS. 1and 2. The liquid typically contains fragments of sponge rubber andfragments of felt, on the order of a quarter inch in diameter, which areused as a carrier for the abrasive material.

U.S. Pat. No. 2,652,662 issued to Newell on Sep. 22, 1953 relates to animproved blasting apparatus which prevents bridging or jamming of theblasting grit material. This is achieved by employing agitating meanssuch as a conduit having a plurality of downwardly directed holes,extending within and across the tank, for discharging a plurality offluid streams into the hopper in order to assure that the blasting gritmaterial is uniformly discharged and does not jam the hopper or opening.The air supplied to the agitating means helps to pressurize the tank.

U.S. Pat. No. 2,910,812 issued to Brunner on Nov. 3, 1959 relates to amethod of moistening black walnut shell grit so that it has greaterimpact and does not tend to accumulate a static charge which causes someof the grit particles to stick to the article being blasted. Thereference teaches an arrangement in which water is sprayed from anozzle, inside chamber, to moisten the black walnut shell grit to abouta 10% moisture content.

U.S. Pat. No. 3,313,067 issued to Smith et al on Apr. 11, 1967 relatesto a process for propelling discrete particles of polycarbonate resinhaving a mean diameter from about 25 mils to about 200 mils. Thepropelled particles have a velocity of between 50 and 300 feet persecond and the particles are sprayed for a sufficient period of time toremove any "flashing" from the surface being treated.

U.S. Pat. No. 4,731,125 issued to Carr on Mar. 15, 1988 relates to asurface cleaning method for removing paint and other coatings fromcomposite surfaces formed of reinforced matrix material. The projectedmedia has a Mohs scale hardness number lower than 3.5 and is acceleratedby air at a pressure of approximately 40 pounds per square inch. Thispatent also indicates that the blasting process has the ability toselectively remove outer layers of material while leaving the underlyinglayers intact.

Although the above-discussed prior art blasting equipment teaches thatthe use of particulate abrasive material to clean a surface iswell-known, such devices are typically only useful for dispensingmaterials of large, individual grain sizes and high density while verypliant and low density materials cannot be effectively used. Moreover,the prior art blasting systems typically rely on gravity feed forinputting the blasting media into the pressurized air stream. Whenattempts are made to dispense a low density material from the knownprior art blasting equipment, it is extremely difficult to obtain aconstant metered flow of the material and bridging, jamming, etc., andother related feed problems quite often occur in such devices.

While the blasting media used in known blasting systems can often berecovered, screened and reused in various manners, in none of the knownrecovery systems is it possible to actually flush liquid contaminantscaptured in the pores of porous grit material, removed from the surfacebeing cleaned, completely from the blasting media. Furthermore, many ofthe blasting materials used by the prior art have the disadvantage ofgenerating substantial amounts of dust and contaminants.

OBJECTS OF THE INVENTION

Wherefore, it is a primary object of the invention to provide acleaning, degreasing and/or desooting apparatus which can use variouslight, pliant materials to accomplish the desired surface treatment ofan object, wall, or other article.

A second object of the invention is to employ a light material which isessentially free from dust and less aggressive to most surfaces than theknown prior art blasting media.

A further object of the invention is to provide a supplycontainer/mechanical feed arrangement which positively meters a desiredquantity of the pliant blasting media into a pressurized air stream.

A still further object of the invention is to provide a system whichallows the pliant blasting media to be recovered, separated, cleaned,flushed and/or dried so that the blasting media can be reused.

An additional object of the invention is to employ porous and/ornon-porous blasting media which can be pretreated with liquids, powders,chemicals and/or solvents, before use, to enhance their action(cleaning, polishing, paint removing, etc.) of the surface.

A further object of the invention is to employ blasting media which ismuch safer for the operator of the blasting device to use and mucheasier to contain because the blasting media only has a minimal tendencyto ricochet off the surface being treated.

Another object of the invention is to provide a media which is useful intreating (cleaning, degreasing and/or desooting) objects containingelectrical wiring and other electronic components without damaging thoseelectrical components.

A still further object of the invention is to reduce the amount ofcontaminated liquid generated during the cleaning and/or degreasingoperation because the media entraps and carries away the contaminants,and does not merely dilute the contaminants.

The term "pliant blasting media", as used herein, means a lightresilient material such as sponge, rubber, plastic or foam, includingboth open and closed cell, as well as other materials, such ashydrophilic sponge having a density of 50 lb/ft.³ or less.

Briefly, the present invention relates to blasting device, suitable fordischarging pliant particulate media against a surface to achieve adesired surface treatment, said blasting device comprising a storagecontainer, having an outlet, for containing a supply of pliantparticulate blasting media; a discharge conduit having nozzle meansconnected to one end thereof; media feed means, connecting the outlet ofsaid storage container to an end of the discharge conduit remote fromsaid nozzle means, for supplying a desired quantity of blasting mediafrom the storage conduit to the remote end of said discharge conduit;air supply means connected adjacent said discharge conduit, forsupplying a flow of pressurized air thereto; and means for substantiallypreventing the back flow of pressurized air into said storage container;wherein said media feed means positively conveys said blasting mediainto said pressurized air flow in said discharge conduit to provide acontinuous supply of blasting media to said nozzle means.

DESCRIPTIONS OF THE DRAWINGS

The above and other objects of the invention will be further understoodby having reference to the accompanying drawings which illustrate, byway of example, the preferred embodiments of the invention, it beingunderstood that other embodiments employing the same basic principalsand falling within the inventive concept may be made as will be readilyapparent to those skilled in the art.

In the drawings:

FIG. 1 is a diagrammatic representation of the pliant blasting mediadevice of the present invention;

FIG. 2 is a diagrammatic representation of a second embodiment of thepliant blasting media device of the present invention;

FIG. 3 is a perspective diagrammatic representation, shown partially cutaway, of an alternative arrangement of the storage container forensuring that a sufficient quantity of blasting media is supplied to thefeed device;

FIG. 4 is a diagrammatic representative of a device for separatingrecovered pliant blasting media;

FIG. 5 shows second embodiment of the feed device for metering asufficient quantity of blasting media into a discharge line;

FIG. 6 shows a flushing apparatus for removing absorbed debris, liquidsand/or chemicals from the pliant blasting media after use;

FIG. 7 is a diagrammatic representation of an alternative arrangement ofthe storage container and feed mechanism;

FIG. 8 is a diagrammatic representation of a further embodiment of thestorage container and feed mechanism; and

FIG. 9 is a diagrammatic representation of a further embodiment of theflushing apparatus for removing absorbed debris, liquids and/orchemicals from the pliant blasting media after use.

Turning first to FIG. 1, which shows a diagrammatic representation ofthe pliant media blasting device 1 of the present invention, the devicecomprises a hopper type storage container 8 which contains a supply ofblasting media 23. The lower portion of the storage container 8 has afunnel-shaped portion 12 having an outlet 12' in the bottom thereof. Anconveyor device 15 connects the outlet 12' of the storage container 8with a discharge conduit or line 18 of preferably a 3/4" I.D. pipe. Theconveyor device 15 comprises a housing having a cylindrical internalbore containing a screw conveyor mechanism 16, driven by motor 10 at adesired rate of speed. The screw conveyer mechanism and the housing havea desired tolerance which ensures positive feeding of the media. Thehousing has an inlet (not shown) connected with the outlet 12' of thestorage container and an outlet 17, remote from the housing inlet,connected with the discharge line 18. The conveyor device 15 positivelyand constantly meters the pliant blasting media 23 from the storagecontainer to the discharge line.

An air supply source 5, such as model no. 185 distributed by theIngresoll Rand Company, has a first air supply line 6 connected to thetop portion of storage container 8 and a second air supply line 7connected adjacent the connection between the discharge line 18 and theconveyer device 15. The air supply source provides pressured air atleast 20 psi, and preferably at about 90 psi. As the blasting mediaenters into the discharge line 18 it is mixed with the pressurized airsupply and then conveyed through the discharge line 18 to a dischargenozzle 20, shown in ghost FIG. 1, where the pliant blasting media isdischarged into a blasting vessel 28 to impact against the object orsurface to be treated. In the above described device, it is to be notedthat the entire blasting device, from the air supply source 5 todischarge the nozzle 20, is pressurized. Alternatively, a non-returnvalve 85 (see FIG. 2) could be positioned between the discharge line 18and conveyer device 15 so that the conveyer device 15 and storagecontainer 8 do not need to be pressurized.

The blasting vessel 28 is a closed container having a bottom, foursidewalls and a removable cover 29. The blasting container 28 typicallyhas a funnel shaped bottom portion 61 which assists in the collectionand recovery of the used blasting media 23'. If desired, a trap door 60can be provided in the bottom of the vessel to facilitate removal of theused blasting media 23'. A supporting surface 24, such as a mesh screenor the like, is provided inside the vessel for supporting the objects100 to be treated. The vessel is useful in batch processing in which theobjects 100 are first placed inside the blasting vessel 28 on thesupport surface 24. Thereafter, the cover 29 is closed and secured inplace and the pliant media blasting device 1 is activated. The media isthen discharged from nozzle 20, positioned inside the blasting container28, against the exterior surface of the objects 100 to be treated toaccomplish the desired surface treatment. Once a sufficient amount oftime has lapsed, the objects are checked and removed if they have beensufficiently treated. Thereafter, a second batch of objects can betreated or if the objects 100 were not sufficiently treated, they can beretreated.

In order to ensure that the pliant blasting media does not bridge or jaminside the storage container 8, and thus freely passes through thefunnel-shaped portion 12 into the conveyer device 15, the storagecontainer 8 is provided with agitation means such as vibrator device 22located on the outside of the container, which shakes the container, ora rotatable agitator 21 (see FIG. 2) provided inside the container,which continuously mixes the media.

Turning now to FIG. 2, this embodiment is similar to that shown in FIG.1 and like elements are represented by like numerals. The majordifference between this embodiment and the embodiment of FIG. 1 is theuse of the agitator 21, located inside the storage container 8, and amotor 10 for rotating the same and the use of a flexible discharge line18', located adjacent the nozzle 20. The rotation of the agitator 21helps prevent bridging and jamming of the blasting media, during use,while the flexible discharge line 18' allows an operator of the blastingdevice 1 to precisely control the discharge direction, impingementangle, duration and other blasting parameters of the surface beingtreated. The device of FIG. 2 can be used in a closed area, such as asmall room or the like, if desired. However, since the pliant blastingmedia only minimally ricochets off the surface, recovery of the blastingmedia is relatively easy regardless of where it occurs.

FIG. 3 shows a trough-type supply tank 13 which could be used instead ofthe supply container 8. Tank 13 is provided with screw conveyor 14 inthe bottom portion thereof for conveying the blasting media to an outlet11 of the tank. The outlet is connected to a discharge line 18 via apositive feed mechanism (not shown) such as the conveyer device 15.

FIG. 4 shows a device for separating used blasting media 23' by itsphysical characteristics (shape, size, resiliency, etc.). The usedblasting media 23' is placed within a completely enclosed media supplycontainer 48. Thereafter, air pressure is provided by air pressuresource 5', via inlet supply conduit or line 51, and this pressurized aircarries a portion of the recovered blasting media 23' contained in thecontainer 48, through a discharge conduit or line 52, to a nozzle 54which directs the blasting media against a deflection plate 55,typically made from metal. As a result of the characteristics of theblasting media 23', it will rebound off the deflection plate and fallinto a second container 58, positioned away from the deflection plate55, where the separated blasting media 23" is collected. The debris andother undesired material 71 are typically not as resilient and thus theywill not rebound as far from the deflection plate 55 and will fall andcollect in a first container 57, located adjacent the deflection plate.Other separation devices, such as a series of appropriately sizedscreens, could also be used to separate the blasting media from thedebris.

FIG. 5 shows an alternate arrangement of the conveyer device 15 which issuitable for positively metering a constant amount of blasting media, ina vertical direction, from the supply container or tank into thedischarge line 18. Such a feed mechanism could be used in combinationwith the trough-like supply tank of FIG. 3, for instance.

FIG. 6 shows a pliant media cleaning apparatus 30 used to removeabsorbed liquids, chemicals and any remaining debris or undesiredmaterial from the separated blasting media 23". The cleaning apparatus30 comprises a container having a bottom 39, a cylindrical sidewall 36and a removable cover 32. An elongate cylindrical perforated wall 25,having a slightly smaller diameter (approximately 1 inches or so) thanthat of the sidewall 36, is positioned inside the containerconcentrically therewith. The perforations in the wall are sized toallow the waste material to pass therethrough but retain the blastingmedia. The region formed between the sidewall 36 and the performed wall25 is in direct communication with a bleed air inlet 80 and an outlet 41of the container, the outlet allows the liquids and debris squeezed fromthe blasting media to be exhausted from the apparatus. The center of thecontainer is provided with a perforated pipe 38, shown in ghost lines,having an expandable bladder 35, made from a durable rubber or otherstrong but resilient material, tightly fastened to its exterior surfaceadjacent the top and bottom of the container. The bladder 35 is shown inits deflated position in FIG. 6. The perforated pipe is supplied withpressurized air via supply conduit or line 47 and air pressure source 5"to thereby inflate the bladder when desired.

The blasting media is placed inside the apparatus 30 between theperforated wall 25 and the deflated expandable bladder 35. Once theapparatus has been filled with sufficient blasting media, removablecover 32 is then positioned to seal the apparatus. Thereafter, airpressure is supplied to expandable bladder 35, via pressure line 47, andthis air pressure inflates the expandable bladder 35 and therebycompresses the pliant blasting media against the perforated wall 25. Asthe bladder 35 is further inflated and expanded it further compressesthe blasting media against the perforated wall and thereby squeezes theabsorbed liquids, chemicals and debris from the media. To assist inremoval of the liquid squeezed from the media by this operation, vacuumcan be applied to the interior of apparatus 30, via a vacuum source 40,vacuum line 43, and outlet 41. The air inlet 80 allows only a smallamount of air to enter into the apparatus so that a desired vacuum ismaintained within the chamber. This vacuum assists with the compressionthe media and carries away the liquid and debris from the apparatus. Theremoved material is collected inside the recovery tank 45 of the vacuumsource 40 where it thereafter can be appropriately disposed of,depending upon its composition. If the media is not adequately cleaned,it can be subjected to additional clean cycles. Other compression means,such as a press and screen arrangement, can be used for removingabsorbed liquids from the blasting media.

It is anticipated that the pressure applied to expandable bladder 35will be between 20 and 60 psi, preferably 45 psi, and the partial vacuumapplied to the apparatus will be between 20 and 22 inches of mercury.This combination of pressure and vacuum will ensure that the flushedblasting media, if unacceptable for reuse, can be safely disposed of ina land fill. However, other pressure and vacuum combinations will alsowork and are considered to be within the spirit and scope of theinvention herein involved.

Turning now to FIG. 7, a third embodiment of the storage container isshown in which the conveyer device 15' and the rotatable agitator 21'are aligned vertically on the same axis and are both rotated by motor10. The rotatable agitator 21' can be provided with a series of paddlesor other agitations members 21" to agitate the media contained withinthe container and ensure the continuous supply of media to the conveyerdevice 15'. The top portion of the container is provided with two doors90, 95 which are both arranged above the motor 10. The first door 90 canbe pivoted open, in the direction of arrow B, to allow additionalblasting media to be added to the top portion of the storage container,i.e. on top of door 95. When the lower portion of the storage container8 requires addition media, the first door 90 is pivoted closed and thesecond door 95 can thereafter be slide in the direction of arrow A toopen the door and allow the blasting media to fall into the storagecontainer without interrupting operation of the device. It is to benoted that both of the doors are provided with air-tight seals whichenable them to withstand the applied pressures.

Turning now to FIG. 8, a still further arrangement for the storagecontainer and feed mechanism is shown and will now be discussed indetail. In this embodiment, the top portion of the storage container 8is open to the atmosphere so that it may be continually supplied withvirgin and/or recycled blasting media 23 during used. The lower portionof the container funnels into a cylindrical shaped elongate portionwhich is provided with a pair of vertically aligned, spaced apartbutterfly valves or other similar valves 70, 72 that are operated bypneumatic, hydraulic or electrical means 74, 76, respectively. Thevalves chosen must be able to achieve an air tight seal, when in aclosed position, which is able to withstand air pressures of about 100psi, or even greater, and 3" butterfly valves manufactured by WattsFluid Air of Portsmouth, N.H. have performed satisfactorily. The twovalves 70, 72 operate independently of one another, i.e. one of thevalves is always closed during operation, so as to maintain thepressurization of the blasting system. The butterfly valves 70, 72 andthe conveyer device 15 divide the lower cylindrical portion of thestorage container into two separate compartments 82, 84 which assistwith batch feeding of the blasting media from the top portion of thestorage container to the conveyor device 15. The first compartment 82 isdefined between the conveyor device and the first butterfly valve 70 andthe second compartment 84 is defined between the first butterfly valve70 and the second butterfly valve 72.

The device operates as follows. Prior to activating the device, both ofthe butterfly valves 70, 72 are moved to an opened position (shown inghost in FIG. 8) by the means 74, 76 and the blasting media 23 suppliedto the top portion of the storage container is this allowed to fall bygravity into and fill the first and second compartments 82, 84.Thereafter, butterfly valves 70 and 72 are closed by the respectivemeans 74, 76 so that an air tight seal is formed by each one of therotatable butterfly valves 70, 72 for maintaining the air pressure ofthe system. Additional blasting media is then placed in the top portionof the storage container and the device is activated so that blasting ofa desired surface can commence. When additional media is required by theconveyor device 15, the first butterfly valve 70 is opened and thisallows the blasting media 23 contained within second compartment 84 tofall, by gravity, into the first compartment 82. The opening ofbutterfly valve 70 also allows the pressurized air of the system topressurize the second compartment 84. Next, butterfly valve 70 is closedand butterfly valve 72 is then opened to allow the blasting media 23contained within the top portion of the storage container to fall withinthe second compartment 84. It is to be noted that as second compartment82 has been pressurized, upon opening of butterfly valve 72 aninstantaneously release of the pressurized air occurs and it impactsagain the blasting media 23 in the top portion of the storage containeradjacent the butterfly valve 72. This air blast helps to loosen theblasting media and prevents bridging or jamming so that a continuoussupply of blasting media is provided to the second compartment 84. Therotation of the butterfly valve 72 also assists with preventing bridgingor jamming. Lastly, the butterfly valve 72 is then closed untiladditional blasting media 23 is required. When this occurs, butterflyvalve 70 is opened so that the blasting media contained in secondcompartment 84 can fall into the first compartment 82 and the aboveprocess is then repeated.

The means 74 and 76 can be operated manually or can be controlledautomatically when a sensor 86, such as a photo electronic sensor or thelike, is provided in the cylindrical portion adjacent the convey means15 to indicate when the first compartment 82 is about to run out ofblasting media. The sensor 86 interacts with the control means 88 whichsequentially activates means 74 or 76 to open automatically the valve 70or 72 for a predetermined length of time so that automatic batch feed isachieved. If manual operation is utilized, a sight glass may beemployed, instead of the sensor 86, to assist the operator withcontrolling the feed of the conveyor device.

Turning now to FIG. 9, a second cleaning apparatus 102 used for removingabsorbed liquids, chemicals, debris or other undesired materials fromthe used blasting media 23 will now be discussed in detail. The cleaningapparatus comprises a washing container 104 into which the used blastingmedia 23 is placed. Water and/or some other cleaning fluid 111 is addedto the container 104 to form a blasting media/liquid slurry 105.Additives, designated diagrammatically by box 150 such as soaps,degreasing agents and the like may be added to the cleaning fluid, ifdesired. A motor 106 is connected with agitating means 108, via asuitable water tight drive connection, to agitate the media/liquidslurry 105 and assist with removing and/or dissolving of the absorbedliquids and solids from the interstices of the blasting media. Tofurther assist with agitation, the slurry can be circulated by pump 112which has an inlet connected with the base of the container 104 byconduit means 110 and has an outlet connected with the top portion ofthe container by return conduit means 114. Once the slurry has beensufficiently agitated so that a majority of the solids, liquids andother debris have been dissolve and/or removed from the blasting mediaand suspended within the slurry, valve 116 of conduit means 114 isclosed and valve 118 of conduit means 120 is opened. This enables thepump 112 to supply the slurry to a centrifuge 122 via the conduit means120. The centrifuge 122 comprises a motor 124 which is connected to arotatable drum 126 via a suitable water tight drive connection. When thecentrifuge 122 is rotated at a sufficient speed, the liquids and otherdebris are thrusted radially outward through a mesh screen, lining theinterior of the rotatable drum 126, thereby separating the cleanedblasting media from its contaminants. A suitable centrifuge could be amodified washing machine, such as a machine manufactured by Sears,Roebuck & Co., and it is anticipated that other similar centrifuges willalso provide satisfactory results. After the centrifuging of the media23 is completed, valve 128 of conduit means 130 is then opened and theliquid separated by the centrifuge is pumped by pump 112, via conduitmeans 130 and 110, to a filter 140. In order for this to occur, valve134 of conduit means 114 must be closed and valves 138 and 142 ofconduit means 136 must be opened. After this pumped liquid has beensufficiently filtered and cleaned by the filter 140, it is then pumpedback into the container 104, by closing valve 138 and opening valve 134,to be used for an additional cleaning cycle. The material 142 removed byfilter 140 then can be appropriately treated, depending on itscomposition, and disposed of properly, e.g. in a land fill or the like.

It is anticipated that the cleaning apparatus can also be automaticallycontrolled by computer means so that the pump, the valves, thecentrifuge and the filter are all timed to occur in a predeterminedsequence. Such automation minimizes the operator attention and rendersthe system more efficient for use.

The present invention allows both the blasting media and cleaning fluidto be used repeatedly and minimizes the amount of end product which hasto be properly disposed of thereby resulting in a system which is veryefficient to operate and has a minimal impact on the environment.

If necessary, a solvent, chemical or other cleansing agent can be addedto the pliant blasting media in the cleaning apparatus and allowed toreact for a time before the cleaning cycle commences. The addition ofsuch additives help dissolve and/or remove harmful liquids or chemicalsfrom the pliant blasting media. In addition, the pliant blasting mediacan be pretreated with a solvent, chemical, cleansing agent, liquidand/or powder, before the blasting media is used in the device 1, toenhance the media's surface treatment. Depending on the amount of liquidabsorbed by the media, this will increase the density of the media andthereby increase its abrasiveness. An important feature of the pliantblasting media is its ability to entrap debris, liquids, solvents, etc.,within its interstices and carry such materials away from the surfacebeing treated.

Since certain changes may be made in the above described pliant mediablasting device, separation device and cleaning system, withoutdeparting from the spirit and scope of the invention herein involved, itis intended that all subject matter contained in the above descriptionand shown in the accompanying drawing shall be interpreted in anillustrated and not in the limiting sense.

Wherefore, I claim:
 1. A blasting device, suitable for dischargingpliant particulate media against a surface to achieve a desired surfacetreatment, said blasting device comprising:a) a storage container,adjacent having an outlet, for containing a supply of pliant particulateblasting media; b) a discharge conduit having nozzle means connected toa first end thereof; c) media feed means, connecting the outlet of saidstorage container to a second end of the discharge conduit remote fromsaid nozzle means, for supplying a desired quantity of blasting mediafrom said storage container to the second end of said discharge conduit,said media feed means facilitating positively conveyance of saidblasting media into a flow of pressurized air in said discharge conduitto provide a continuous supply of blasting media to said nozzle means;d) air supply means connected adjacent the second end of said dischargeconduit for supplying the flow of pressurized air thereto; e) means forsubstantially preventing back flow of pressurized air into said storagecontainer; f) means for washing a slurry formed from a cleaning liquidand the used blasting media to remove debris and other contaminants fromthe used blasting media; g) means for centrifuging the slurry toseparate the cleaned blasting media from the cleaning liquid, debris andother contaminants; and h) means for filtering the cleaning liquid,debris and other contaminants to separate the debris and othercontaminants from the cleaning liquid.
 2. A blasting device according toclaim 1, wherein said means for preventing back flow is first and secondair tight valve means sequentially located adjacent the outlet of saidstorage container.
 3. A blasting device according to claim 2, whereinthe outlet of said storage container comprises an elongate portion andsaid first and second valve means divide the elongate portion into saidfirst and second compartments, said first and second valve means beingsequentially operatable for transferring blasting media from saidstorage container to said media feed means via said first and secondcompartments.
 4. A blasting device according to claim 3, wherein saidfirst compartment is defined between said media feed means and saidfirst valve means, and said second compartment is defined between saidfirst valve means and said second valve means, each of said first andsecond valve means has motor means for activating the valves means asdesired.
 5. A blasting device according to claim 1, wherein said mediafeed means comprises a motor and a housing containing a screw conveyor,said housing has an inlet for receiving blasting media from the outletof said storage container and an outlet for supplying blasting media tosaid discharge conduit.
 6. A blasting device according to claim 2,wherein said first and second valve means are a pair of butterfly valvesindependently operated by motor means.
 7. A blasting device according toclaim 4, wherein sensor means are provided in said first compartment tosense when additional blasting media is required by the conveyor device,said sensor means communicating with control means, connected with themotor means of said first and second valve means for automaticallycontrolling the flow of blasting media into said media feed means.
 8. Ablasting media according to claim 1, wherein said air supply meansprovides at least 20 psi of air pressure to said blasting device.
 9. Ablasting device according to claim 8, wherein said air supply meansprovides approximately 90 psi air pressure to said blasting device. 10.A blasting device according to claim 1, further comprising agitatingmeans, associated with the storage container, for agitating the blastingmedia within the container to ensure that a continuous supply ofblasting media is fed to said media feed means.
 11. A blasting deviceaccording to claim 1, wherein said device further includes:a) means forseparating the blasting media from debris and other contaminants afteruse so that the blasting media is reusable; and b) means for collectingthe removed debris and other contaminants from the blasting media fordisposal.
 12. A blasting device according to claim 1, wherein saiddevice further includes means for removing absorbed liquids andcontaminants from the media after use.
 13. A blasting device, suitablefor discharging pliant particulate blasting media against a surface toachieve a desired treatment of that surface, said blasting devicecomprising:a) a storage container, for containing a supply of pliantparticulate blasting media, having an outlet; b) a discharge conduithaving a discharge nozzle connected to a first end thereof; c) airsupply means connected adjacent a second end of said discharge conduitfor supplying a flow of pressurized air thereto; d) media feed means,connecting the outlet of said storage container adjacent the second endof the discharge conduit, for supplying a desired quantity of blastingmedia from said storage container to the second end of said dischargeconduit, said media feed means facilitating positive conveyance of saidblasting media into said flow of pressurized air in said dischargeconduit to provide a continuous supply of blasting media to said nozzle;e) means for preventing back flow of the pressurized air flow into saidstorage container; f) means for forming, after use of the blastingmedia, a liquid slurry of a cleaning liquid and the used blasting mediafor facilitating removal of absorbed debris and other contaminants fromthe used blasting media; and g) means for separating the cleanedblasting media from the cleaning liquid, debris and other contaminantsso that the cleaned blasting media may be reused.
 14. A blasting deviceaccording to claim 13, wherein said blasting device further includesmeans for supplying an additive to the slurry of the cleaning liquid andthe used blasting media for facilitating removal of the absorbed debrisand other contaminants from the used blasting media.
 15. A blastingdevice according to claim 13, wherein said blasting device furtherincludes means for separating the debris and other contaminants from thecleaning liquid to facilitate reuse of the cleaning liquid and properdisposal of the debris and other contaminants.
 16. A blasting deviceaccording to claim 13, wherein said means for forming a slurry furtherincludes agitating means to agitate the slurry and assist with removingthe debris and other contaminants from the used blasting media.
 17. Ablasting device according to claim 13, wherein said means for separatingthe blasting media from the cleaning liquid, debris and othercontaminants comprises a centrifuge mechanism driven by a motor at asufficient speed.
 18. A blasting device according to claim 17, whereinthe centrifuge mechanism includes an outlet which is connected with aninlet of filter means for filtering the cleaning liquid, debris andother contaminants to separate the debris and other contaminants fromthe cleaning liquid.
 19. A blasting device according to claim 18,wherein said filter means includes an outlet which is connected withsaid means for forming a slurry for supplying the filtered cleaningliquid thereto to facilitate reuse of the cleaning liquid.
 20. Anapparatus for treating a contaminated surface with a plurality ofdiscrete, individual particles of a pliant particulate blasting mediacapable of absorbing a contaminate from the contaminated surface, saidapparatus comprisinga) means for containing a supply of said pliantparticulate blasting media; b) a discharge conduit having a first endand a second end, the second end facilitating discharge of said pliantparticulate blasting media against the contaminated surface forabsorbing the contaminate from said contaminated surface; c) means forpositively conveying said pliant particulate blasting media from saidstorage means to the first end of said discharge conduit; d) means forsupplying air flow under pressure to the first end of said dischargeconduit whereby the pressurized air flow and said positively conveyedpliant particulate blasting media mix together in said discharge conduitto form a pressurized air and blasting media mixture; wherein saidapparatus is used in combination with: e) a dry light resilientabsorbent cellular material pretreated with a dry powder to increase thedensity and the abrasiveness of the cellular material which comprisessaid pliant particulate blasting media.
 21. A surface treatmentapparatus according to claim 20, wherein said apparatus further includesmeans for preventing jamming and bridging of the cellular material, insaid means for containing a supply of said pliant particulate blastingmedia, to ensure a continuous supply of said cellular material blastingmaterial to said means for positively conveying said cellular materialblasting media.
 22. A surface treatment apparatus according to claim 20,wherein said apparatus further includes:a) means for separating absorbeddebris and other contaminants from said cellular material blasting mediaafter use so that said cellular material blasting media is reusable; andb) means for collecting the removed debris and other contaminants fromsaid cellular material blasting media for disposal.
 23. A surfacetreatment apparatus according to claim 20, wherein said apparatusfurther includes means for removing absorbed liquids and contaminantsfrom said cellular material blasting media after use.
 24. In anapparatus for treating a contaminated surface with a plurality ofdiscrete, individual particles of a pliant particulate blasting mediacapable of absorbing a contaminate from the contaminated surface, saidapparatus comprisinga) means for containing a supply of said pliantparticulate blasting media; b) a discharge conduit having a first endand a second end, the second end facilitating discharge of said pliantparticulate blasting media against the contaminated surface forabsorbing the contaminate from said contaminated surface; c) means forpositively conveying said pliant particulate blasting media from saidstorage means to the first end of said discharge conduit; d) means forsupplying air flow under pressure to the first end of said dischargeconduit whereby the pressurized air flow and said positively conveyedpliant particulate blasting media mix together in said discharge conduitto form a pressurized air and blasting media mixture; wherein saidpliant particulate blasting media comprises a dry light resilientabsorbent cellular material pretreated with a dry powder to increase thedensity and the abrasiveness of said cellular material for enhancedsurface treatment.